When is zakat due on money that has reached the nisab, then its owner bought a car for his private use with it five months before the completion of the hawl, then sold it two months later due to defects in it and lost part of its price, and this money was not spent?

Regarding money, it begins from the time the car is sold, and zakat becomes due on it if a full year passes. Its year does not begin from the first year before the purchase because buying the car ends the first year, and selling it initiates a new year. This ruling is specific to someone who bought something for personal use and then decided to sell it. For a new year to begin, two conditions are required: that the purpose of selling is not to evade zakat, and that the purchase was intended for personal use, not for trade. If it was intended for trade, then the first year is maintained.